linux-kernel - Re: [PATCH 06/27] Copy secure_boot flag in boot params across kexec reboot

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Date:   Fri, 20 Oct 2017 14:40:00 +0800
From:   joeyli <jlee@...e.com>
To:     David Howells <dhowells@...hat.com>
Cc:     linux-security-module@...r.kernel.org, gnomes@...rguk.ukuu.org.uk,
        linux-efi@...r.kernel.org, matthew.garrett@...ula.com,
        gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
        jforbes@...hat.com
Subject: Re: [PATCH 06/27] Copy secure_boot flag in boot params across kexec
 reboot

On Thu, Oct 19, 2017 at 03:51:20PM +0100, David Howells wrote:
> From: Dave Young <dyoung@...hat.com>
> 
> Kexec reboot in case secure boot being enabled does not keep the secure
> boot mode in new kernel, so later one can load unsigned kernel via legacy
> kexec_load.  In this state, the system is missing the protections provided
> by secure boot.
> 
> Adding a patch to fix this by retain the secure_boot flag in original
> kernel.
> 
> secure_boot flag in boot_params is set in EFI stub, but kexec bypasses the
> stub.  Fixing this issue by copying secure_boot flag across kexec reboot.
> 
> Signed-off-by: Dave Young <dyoung@...hat.com>
> Signed-off-by: David Howells <dhowells@...hat.com>
> cc: kexec@...ts.infradead.org

I have reviewed and tested this patch. Please feel free to add:

Reviewed-by: "Lee, Chun-Yi" <jlee@...e.com>

Thanks a lot!
Joey Lee

> ---
> 
>  arch/x86/kernel/kexec-bzimage64.c |    1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
> index fb095ba0c02f..7d0fac5bcbbe 100644
> --- a/arch/x86/kernel/kexec-bzimage64.c
> +++ b/arch/x86/kernel/kexec-bzimage64.c
> @@ -179,6 +179,7 @@ setup_efi_state(struct boot_params *params, unsigned long params_load_addr,
>  	if (efi_enabled(EFI_OLD_MEMMAP))
>  		return 0;
>  
> +	params->secure_boot = boot_params.secure_boot;
>  	ei->efi_loader_signature = current_ei->efi_loader_signature;
>  	ei->efi_systab = current_ei->efi_systab;
>  	ei->efi_systab_hi = current_ei->efi_systab_hi;
> 
> --
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